Enhanced boiling heat transfer on surfaces patterned with mixed wettability

Biao Shen, Masayuki Yamada, Tomosuke Mine, Sumitomo Hidaka, Junichiro Shiomi, Gustav Amberg, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata

Research output: Contribution to journalConference article

1 Citation (Scopus)

Abstract

Amongst an extensive collection of surface characteristics that could affect boiling performance, surface wettability (as measured by the contact angle with water) proves to play a unique role in potentially manipulating bubble behavior to the advantage of higher heat transfer rates. In this study, we show experimentally that controlled bubble behavior be realized under the surface design incorporating these two characteristics (namely, by coating an array of hydrophobic spots on a hydrophilic substrate), which leads to a great enhancement in boiling heat transfer under various conditions. In reduced-pressure pool boiling, the strong pinning of the bubble contact line at the border between the hydrophilic and hydrophobic regions manages to prevent total deactivation of nucleation sites. As a result, the deleterious transition to intermittent boiling is effectively delayed, whereby no heat transfer deterioration occurs until a very low pressure of about 8 kPa is reached. Moreover, in subcooled boiling, bubble growth on a patterned surface is found to be facilitated by a pronounced presence of dissolved gas in defiance of exhaustive degassing efforts through continuous boiling, thanks to an unusually strong retention of gas contents by the hydrophobic surface. As experimental and numerical evidence show, only bubbles with sufficiently high concentrations of gas components (i.e., causing weakened condensation) are able to grow large enough on the hydrophobic surface such that periodic pinch-offs might take place, which is responsible for most of the initial heat transfer enhancement before large-scale bubble nucleation starts on the hydrophilic surface as well.

Original languageEnglish
Pages (from-to)1379-1386
Number of pages8
JournalInternational Heat Transfer Conference
Volume2018-August
DOIs
Publication statusPublished - 2018
Event16th International Heat Transfer Conference, IHTC 2018 - Beijing, China
Duration: Aug 10 2018Aug 15 2018

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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